'The Voice': Gwen Stefani threatens to quit after battling teens nail John Legend song

It's the battle of the teens on "The Voice." 

Gwen Stefani's Larriah Jackson, 15, and Carter Rubin, 14, kicked of the final Battle Round Monday with a duet of Meghan Trainor and John Legend's "Like I'm Gonna Lose You."

And if performing on a big stage early in your career isn't enough pressure, imagine singing John Legend's song in front of John Legend.

"Oh, so John Legend is going to be right there," Rubin said after being assigned the song. "It’s intimidating to be one of the younger ones because everyone here is so insanely talented."

The tiny powerhouses didn't crack under pressure and sang like true veterans, earning a standing ovation from the coaches. 

'The Voice': Kelly Clarkson speechless after contestant ‘sang the crap out of' her song

'The Voice': Gwen Stefani threatens to 'quit' after teen singers nail John Legend feature

"That was so well done. … Like, you are 14 and 15," said Kelly Clarkson, who couldn't offer Stefani any guidance on who she would dub the winner, telling her, "You are so screwed." Blake Shelton told reminded the coach she's "contractually obligated to pick."

Legend approved of the performance: "Usually I’m very judgey when it comes to songs I recorded, but I was thoroughly impressed with your take on the song."

The "All of Me" singer leaned toward Rubin's performance. "Carter, you know I wanted you on my team. I was a little bit hurt when you didn’t pick me."

"Why are you shaming a 14-year-old," Clarkson clapped back. 

However, the final decision was up to Stefani. And she almost didn't make one.

As host Carson Daly pressured Stefani for her final verdict, the No Doubt rocker rose out of her signature red chair, declaring, "I’m going to quit now."

"That was the worst thing ever, to have to choose," Stefani said. "They were equally so deserving to move forward.". 

In the end, Stefani picked Rubin as the winner. And she quickly used her save to keep Jackson on her team, too: "You have too much to give to the world, so I’m so glad I got to save you."

'The Voice':John Legend, Blake Shelton battle it out for this (double) steal-worthy duet

That meant Shelton was the only one left with a steal.

"I think premature button-pushing is a problem with these other three coaches," Shelton said. "I don’t know why in the world you would use your steal button in the first couple of Battles. You really got to settle down."

His strategy played out well during the final Battle between Legend's Cami Clune, 20, and James Pyle, 30, who gave a "haunting" duet of Chris Isaak’s "Wicked Game."

"If I had a steal left, I would be all up on this button. But I don’t," Clarkson said. And leave it to Shelton to rub it in. 

After Legend dubbed Clune the winner, Shelton paused the whole competition. "Wait, wait, wait, I want to see If this still works," he said before pressing the steal button for Pyle. 

Clarkson gave Shelton props: "Well played."

Even Legend was complimentary. "Blake came through. He disappoints me a lot, but he came through."

"The Voice" continues Tuesday at 8 EST/PST on NBC with the first Knockout Round.